Telephone system



5 Sheets-Sheet l C. E. LOMAX TELEPHONE SYSTEM Filed April 28, 1939 k' 3: Q9 RE og f. 4 .w EE

om: EW QNE EQBEB: F g

Dec. 31, 1940.

INVENTOR.

CLARENCE E LOMAX ATTORNEYS.

D136. 31, 1940. c LOMAX TELEPHONE SYSTEM Filed April 28, 1939 5 Sheets-Sheet 5 IN\QHVTOR.

, CLARENCE E. LOMAX BY IOM,M WM

ATTORNEYS Dec. 31, 1940. c. E. LOMAX TELEPHONE SYSTEM Filed April 28, 1959 5 Sheets-Sheet 4 wsg INVENTOR ATTORNEYS.

CLARENCE E LOMAX i k. @b

Dec. 31, 1940. c. E. LOMAX TELEPHONE SYSTEM 5 Sheets-Sheet 5 Filed April 28, 1939 93m w m 2 mgo BU BQE I V a T ESQ 98. KSQ 3X mwzvluxm qzoowm INVENTOR. CLARENCE E LOMAX WW, MM

ATTORNEYS.

Patented Dec. 31, 1940 TELEPHONE SYSTEM Clarence E. Lomax, Oak Park, Ill., assignor to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application April 28, 1939, Serial No. 270,538

43 Claims.

The present invention relates to .telephone systems and, more particularly, to improved apparatus for controlling the collecting and refunding of coins deposited in the coin-receiving means of paystations forming a part 'of an automatic telephone system.

In the usual automatic telephone system, a portion of the substations are of the paystation type, each including means for receiving coins, slugs, or the like, and a coin control mechanism for controlling the coin refunding and collecting operations normally required incident to use of the station. Accordingly, the automatic switching apparatus of the system must be suitably arranged automatically to control the paystation control mechanism incident to the use of local connections involving the paystations and must include apparatus for permitting operators selectively to control the mechanisms so that the proper charges and collections may be made incident to the use of toll connections involving the paystations. Prior automatic telephone systems including these paystation control features are more or less complicated in arrangement and include a large amount of equipment which is used only for the purpose of effecting proper con- ,trol of the coin mechanisms provided at the pay stations. For example, complicated and specially designed intermediate and final selector switches are usually provided for enabling toll operators to set up delayed call connections to the paystations and for permitting the proper coin collecting and refunding operations to be made. In the usual arrangement these special switches are used only in setting up toll call connections.

Moreover, prior paystation trunk circuits, in general, require a large amount of relay equipment for effecting the proper control of the paystation coin control mechanisms.

It is an object of the present invention to provide, in an automatic telephone system, improved and exceedingly simple apparatus for controlling the coin collecting and refunding operations required incident to the use of connections involving the paystations embodied in the system.

It is .another object of the invention to provide, in an automatic telephone system, improved and simplified apparatus whereby an operator can control the collecting and refunding of coins deposited at the paystations of the system at which calls originate or to which calls are routed.

It is a further object of the invention to provide improved apparatus of the character described which is so arranged that the regular automatic switching apparatus of the system may be used in completing both local and toll connections without sacrificing any of the required paystation control features.

It is a further object of the inventionto provide for use in an automatic telephone system an improved final selector switch which is adapted to be used in completing both local and toll connections involving both regular andpaystation lines and has embodied therein improved and exceedingly simple apparatus controllable from an operators position for efi'ecting coin collecting and refunding operations at paystations associated with certain of the lines accessible to the switch.

It is another object of the invention to provide for use in an automatic telephone system an improved two-way repeater which is adapted to be used in completing toll connections involving both regular lines and paystation lines and has embodied therein improved and simplified apparatus for effecting coin collecting and refunding operations required incident to the use of the paystations included inthe system.

It is a still further object of the invention to provide improved and exceedingly simple paystation circuit apparatus adapted for use in conjunction with the trunk linesincoming to certain of the first numerical switches of an automatic telephone system and which is 50 arranged that all required paystation control operations are efiected with a minimum amount of equipment.

It is a further and more specific object of the inventionto provide improved paystation control apparatus of the character described wherein booster battery control is utilized in efiecting coin refunding and coin collecting operations.

In the illustrated embodiment of the invention there is disclosed an automatic telephone system which includes a plurality of lines, one of which extends to a substation of the paystation type,

together with automatic switching apparatus including a group of final selector switches, which apparatus is operative-to establish connections between thevarious lines. There is also embodied in the system an operator's position to which toll calls may be routed from the substa- 2 asaeaso of final selector switches mentioned above, which apparatus is, in each case, controllable from the operator's position to control the coin refunding and collecting control means provided at the pay- 5 station to cause coins deposited in the coin-receiving means to be refunded or collected, as desired. This apparatus in no way prevents the switches from being utilized in completing local call connections, On the contrary, the arrangement is such that these switches may be utilized in extending calls to and from the operator's position on calls involving any of the substations of the system and in setting up local call connections between any of the lines of the system. More particularly, this apparatus as embodied in each switch is operative in response to operation of the calling device conventionally provided at the operator's position, after a connection has been routed from the operator's position to the paystation, to cause the coin collecting and refunding control means to operate in a particular manner, 1. e., to refund coins deposited in" the coin-receiving means. This apparatus, as embodied in each switch, is further arranged to respond to an unbalanced condition of an established loop circuit extending to the corresponding switch to cause the above-mentioned coin refunding and collecting control means to operate in a diiferent manner, i. e., to collect coins de- 80 posited in the coin-receiving means.

The above-described coin control apparatus is primarily utilized in controlling the coin collecting and refunding control means on calls routed from the operator's position to the above-men-' s5 tioned paystation. In regard to calls routed in the opposite direction, certain of the first numerical switches of the system have associated with the trunk lines incoming thereto paystation circuits which function, on toll calls routed to the 40 operator's position, only to control the coin refunding and collecting control means in its operation to eifect a coin collecting operation. These trunk circuits, on local calls originating at the paystation, are arranged to operate in a novel 45 manner to cause both coin refunding and collecting operations to be performed. Two embodiments of this improved trunk circuit apparatus are disclosed. In one embodiment of this apparatus reverse battery control is utilized and 60 in the other embodiment the arrangement is such that booster battery control may be utilized. For the purpose of obtaining coin refunding operations on toll calls routed to the operator's position, the repeaters individually associated with 68 the trunk lines extend-ing to the operator's position are provided with apparatus, arranged in an improved manner and controllable from the operator's position, for imposing upon an established connection extending back to the paystaso tion a predetermined coin refund potential.

Further features of the invention pertain to a the particular arrangement of the various switching elements, whereby the same switches may be used in completing both local and toll connections,

es and the required paystation trunk circuit apparatus for effecting control of the coin refunding and collecting control means is reduced to a a minimum.

The novel features believed to be characteristic 70 of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the 7s specification taken in connection with the accompanying drawings, in which Figures 1 to 5. inclusive, when combined in the manner shown in Fig. 7, illustrate a telephone system having incorporated therein the features of the invention as briefly outlined above; and Fig. 6 illus- 5 trates a modification of certain of the apparatus shown in Fig. 1.

In general, the system, as illustrated in Figs. 1 to 6, inclusive, of the drawings, comprises a relatively small community automatic exchange and 10 a second central exchange, the two exchanges being interconnected by a plurality of two-way trunk lines, one of which is indicated at Ill in Fig. 5 as extending to the operator's position ll provided in the central exchange. In the particular 15 arrangement shown. the community automatic exchange is designed to serve one hundred lines or less. Two of these lines are indicated at Ii and I2 as extending respectively to the substations A and B, the substation A being of the pay- 20 station type'and the substation B being of the conventional common battery type of which there are several well-known commercial embodiments. The line I2 and the other similar lines may be of the single party type or of the multiparty type, 25 as desired. For the purpose of setting up connections between the lines terminating at the community exchange, there is provided automatic switching equipment which comprises a plurality of line switches, two of which are indicated at II and II, individually associated with the subscribers lines of the system and a plurality of connector switches, one of which is illustrated in Figs. 2 and 3. These connector switches each have access to all of the lines terminating 5 at the community exchange and also to repeaters individually associated with the trunk lines extending to the central oflice. Thus. the connector switch shown in Figs. 2 and 3 has access by way of a link line l3 to a two-way repeater I8 associated with the two-way trunk line l0. Calls routed from the central exchange over the trunk line l0 and intended for a subscriber's line terminating in the community exchange may be routed through the repeater I8 and any one of the connector switches provided in the community exchange to the desired subscriber's line. To

. this end, there is associated with the link line II a line switch II which has access'to the trunk lines individually incoming to the various connector switches.

Any desired number of the subscribers lines terminating at the community exchange may be arranged to serve substations of the paystation type and such substations may each be of the form illustrated in Fig. 1 for the substation A. In brief, the apparatus provided at this substation comprises a transmitter I M, a receiver lili and an induction coil Ill! arranged to be interconnected through operation of a hook switch I" to form a substation circuit of the well-known anti-side-tone type. For the purpose of audibly indicating the presence of incoming calls on the line H, there is also provided at the substation A a signal device in the form of a ringer III which is bridged across the conductors l I. and II of the line il in series with a condenser II. In order to transmit switch control impulses by way of the line II to the automatic switching equipment provided in the line terminating exchange, there is embodied in the substation apparatus a calling or impulsing device Ill. The substation further comprises coin-receiving means, not shown, which includes a coin deposit chute, a coin collect chute and a coin refimd aaaarao 3 chute. together with apparatus for selectively di-' recting a deposited coin into the correct one of the coin j collect and coin refund chutes- This apparatus includes a coin-directing door. not 5 shown, which is arranged to be operated by a polarized electromagnetic device I" having windings adapted to be connected between the line conductors II. and ground in series with a glow discharge device in the form of a neon tube IN. The electromagnetic device I" is so arranged thatwhen its windings are energized by current of one polarity the associated coin-directing door is rocked in one direction to direct deposited coins into the coin refund chute. The

when its windings are energized by current of the opposite polarity the associated coin-directing door is rocked in another direction to direct deposited coins into the coin refund chute. The neon tube I08 has the well-known characteristic of being non-conductive until a predetermined voltage is impressed across the terminals thereof. Following ionization of the gas contained therein the voltage required to maintain the tube conductive is substantially less than that required for initiating ionization. Also, the resistance of the device is substantially lessened after the device is rendered conductive. The series circuit including the tube "18 and the windings of the device I01 also includes a pair of contact springs I09 which are only operated into engagement in response to the deposit of a coin in the coin deposit chute of the coin-receiving means. when once operated into engagement, the springs I89 are not disengaged until the electromagnetic de- 'vice I01 operates in one manner or the other.

The coin collect apparatus provided at the substation A and schematically shown in Fig. l of the drawings may be of the well known type shown and described in Patent No. 1,043,219,

40 granted November 5, 1912, Forsberg, although preferably this apparatus and the impulsing device IIIA of the substation are arranged in, the

manner disclosed and claimed in copending application Serial No. 265,459, filed April 1, 1939,

Clarence E. Lomax. As thus arranged, certain calls, such, for example, as trunk calls to an operator's position in the distant central ofllce, may successfully be completed without the deposit of a coin in the coin-receiving means, whereas other calls intended for the substations local to the community exchange can only successfully be completed after a coin has been deposited in the coin-receiving means. To this end, and as disclosed in the aforementioned copending application, the substation circuit is so arranged that only a predetermined number of digits, as, for example, two digits, may eifectively be transmitted from the substation, a digit counter being provided for shunting the pulsing springs of this 50 device after a predetermined number of digits has been dialed.

For the purpose of controlling the coin collecting and coin refunding operations required incident to the use of connections resulting from 65 calls originating at the substation A, each trunk line extending to the bank contacts of the line switch i5 and incoming to one of the connector switches embodied in the community exchange is divided into two parts which are connected 70' by paystation trunk circuit apparatus. Thus, the trunk line 2B.incoming to the connector switch shown in Figs. 2 and 3 is connected to a. set of bank contacts in the line switch it and to the other similar line switches associated with lines 75 of the paystation type through a trunk circuit I! which includes a group of relays for controlling the coin collecting and coin refunding operations performed incident to use of the substation A. More particularly, this trunk circuit comprises a coin control and line switching relay 5 RI arranged to be controlled by a pair of additional relays RIM and RI 50, the first of which is of the slow-to-release type. These two additional relays also function, when operated, in the capacity of hold relays in that they impress lo ground potential upon the release or control conductor of the trunk line section extending to the line switch I. The trunk circuit H further includes an electropolarized relay Rl3ll which functions to determine whether a coin refund or 15 coin collect operation is to be performed incident to operation of the relay Ri20. This polarized relay comprises an upper winding serially included in one side of the trunk line extendipg to-the connector switch shown in Figs. 2 and 20 3 and shunted by a resistor I32 for by-passing voice frequency currents. This relay is so constructed and arranged that it only operates when its lower winding is polarized and current of a predetermined polarity is directed through its 25 upper winding. When once operated, however, the relay l'tlfli remains opera-ted so long as its lower winding is energized and regardless of the polarity of the current traversing its upper winding. Several embodiments of this type of relay 30 :are commercially available.

On a call originating at a .paystation, such, for example, as the station A, and routed to an operator's position in the central ofilce, it is necessary that apparatus be provided for disclosing to the operator the identity of the calling station in order that the proper charges maybe assessed and the proper collection made. For this purpose there is provided a tone generator 2i which is arranged to impress its alternating volt- 40 age output upon the control conductor I I0 of the line H through a condenser v22. In order to transmit the paystation tone voltage through the trunk circuit apparatus to the control conductor of the connector switch shown in Figs. 2 and 3 45 on calls routed by way of this switching equipment, there is provided a condenser 22.

Since the trunk circuit apparatus I l is provided only for the purpose of controlling coin collecting and coin refunding operations incident 50 to the use of substations of the paystation type on calls originating at such substations, it will be apparent that there is no need to include this or similar apparatus in the trunk lines extending between the line switches associated with the 55 regular substation lines and the connector switches. Accordingly, the trunk line 20 extending to the connector switch shown in Figs. 2 and 3 is terminated directly in the bank contacts of the line switch l5 associated with the subscribers line l2 and in the corresponding bank contacts of the line switch it associated'with the link line i8 extending to the repeater 18.

Each of the line switches embodied in the automatic switching apparatus provided in the community exchange is preferably of the well-known rotary type of which several commercial embodiments are known. The connector switches of this exchange are all of identical arrangement. In brief, the connector switch shown in Figs. 2 and 3 comprises a plurality of bank contacts arranged in levels; a wiper carriage structure including the wipers 3H to 364, inclusive; means comprising a vertical magnet 246 for elevating the wiper carriage structure to 'bring the wipers opposite a desired level or contacts: means comprising a rotary magnet 342 for rotating the indicated wipers until they engage a desired set of contacts in a selected level: a release magnet 221; three sets of off-normal springs 203, 224 and 245 and a plurality of control relays connected and arranged in the manner illustrated. More particularly, the control relays of the connector switch include a line switching relay R200 of the slow-torelease type, a called party answer or back-bridge relay R2I0, a line relay R230, 9. slow-to-release hold relay R235, a slow-to-release digit transfer relay R240, a ring cut-oi! relay R250, a ringing control relay R260, a pair of booster battery control relays R200 and R235, a busy test relay R300, a pair of slow-to-release pulse responsive relays R3I0 and R320, and a slow-to-operate line switching relay R330. The slow-acting relay R320 is arranged to cooperate with a trunk hunting relay R325 to control the operation of the wipers I to 334, inclusive, when the connector switch is functioning to search for an idle one of the trunk lines extending to the central oflice. The control apparatus of the connector switch further includes four additional relays R220, R225, R340 and R345 which are provided for the purpose of controlling coin refunding and coin collecting operations performed incident to the completion of calls routed from an operators position in the at the community exchange. In order to transmit paystation tone voltage impressed upon the control conductor 20.; of the trimk line 20 incoming to the connector switch to the control conductor of a link line extending to one of the repeaters selected through operation of the connector switch, there is also embodied in the connector switch a signal voltage repeating transformer 2I6.

The connector switch is arranged to provide selective code ringing of the substations associated with the multiparty subscribers lines of the system. To this end there is embodied in the connector switch an impulse responsive code selecting switch 350 of the well-known minor type.

'In brief, this code selecting switch comprises two sets of bank contacts 35I and 352 of eleven points each; wipers 353 and 354 individually associated with the contact sets; means comprising an operating magnet 356 and a ratchet and pawl mechanism, not shown, for stepping the wipers over the contacts of their respective associated contact sets: a release magnet 351; and off-normal springs 358 for controlling the energization of the release magnet.

The two-way repeater I8 associated with the trunk line I0 extending between the community exchange and the central office comprises a repeating transformer 520 and a plurality of relays for controlling the signaling and line switching operations required incident to the extension of connections in either direction through the repeater. More particularly, the relay equipment of this repeater comprises a line relay R400, a slow-to-release hold relay R4I0, a ringing relay R420, a ring cut-oil relay R430, and a pair of relays R440 and R450 which function to control the transmission of the paystation tone signal voltage over the trunk line I0 to the operator's position I0. The relay R440 is of the slow-tooperate type and the relay R450 is of the wellknown pendulum type. The relays just described are utilized primarily in the extension of connections from the apparatus provided in the community exchange to the operator's position I9. On calls routed in the other direction, that is, from the operator's position I3 to the automatic switching apparatus provided In the community exchange, the relay equipment shown in Fig. 5 primarily controls the line switching operations. This equipment comprises a line relay R530, a back-bridge relay R550, 8. slow-acting line switching relay R510, and a control relay R560, Two additional relays R540 and R460 are embodied in the repeater I0 for the purpose of controlling coin refunding operations required incident to the use of paystations associated with the paystation lines terminating at the community exchange. For the purpose OLtransmitting paystation tone signals over the trunk line I0, there is embodied in the repeater a transformer 455 which includes a primary winding 468, bridged between the control conductor I31: of the link line I3 and ground, and a secondary winding 46! which is adapted to be bridged across the line conductors of the repeater in series with a condenser 458.

The trunk line I0 terminates in the central exchange in a repeater transformer 500, one side of which is connected to the tip and ring contacts of a call and answer Jack 50I located at the operators position I9. The apparatus provided at the operators position I9 also includes a signal device in the form of a drop 502 which includes a winding normally bridged between ground and the junction point of the secondary windings of the transformer 500 in series with a condenser 503. For the purpose of transmitting switch control impulses from the operators position I9 over the trunk line I0 to the repeater I8, there is provided a calling or impulsing device 504. The apparatus provided at this operators position further includes a coin refunding and collecting control key 505 of the non-locking type which is operative to impress the positive potential of a booster battery current source 5| I upon a simplex circuit including the trunk line I0, thereby to control the two relays R540 and R460 embodied.

in the repeater I8. The apparatus provided at the operator's position I9 also includes an operators cord circuit, not shown, which may be of any desired commercial arrangement.

As explained above, the arrangement of the apparatus provided at each of the substations of the paystation type is such that a local call initiated at any one of these substations can only be completed if the correct coin deposit is made in the coin-receiving means provided at the calling substation. Assuming, for example, that a party at the substation A desires a connection with the substation B, the call is initiated in the usual manner by removing the receiver IOI from the supporting hook H4 of the hook switch I03. In response to this operation a loop circuit is completed for initiating the operation of the line switch I4. This loop circuit may partially be traced as extending by way of the line conductor I la, the pulsing springs II3, the transmitter I00, the switchhook H4 and associated contacts I I5 and H6, and the induction coil winding I I2 to the opposite line conductor IIs. When the hook switch I03 is operated to its off-normal position the contact springs II3 are also closed so that the induction coil I02, the transmitter I00 and the receiver IOI are properly interconnected for the reception and transmission of voice frequency currents. The line switch I4 responds to the completion of the above-traced loop circuit by operating in a well-known manner to select a trunk line extending to an idle one of the conaaaepao nector switch to which it has access. Assuming, for example, that the connector switch illustrated in Figs. 2 and 3 is the first available idle switch accessible to the line switch I4, when the 5 trunk line extending to this connector switch is found, the line switch I4 operates to extend the calling loop circuit to this connector switch, so that the line relay R230 is energized. More particularly, the circuit for energizing the line relay R230 may be traced as extending from ground by way of RA242, the lower winding of R230, the lower winding of R225, RA2I5, RC208, RA201, the line conductor 20b, the upper winding of RI30, RAI22, the conductor b, the winding 16 H2, the contacts H6 and H5, the'switchhook N0, the transmitter I00, the pulsing springs II8, the conductor a, RAIZI, the conductor 20a, RA202, RC203, RA2I3, the upper winding of R225 and the upper winding of R230 to battery. The relay R225, being of the diiferentlal type, does not operate when its two windings are energized over the loop circuit justtraced. The relay R230, however, operates to complete, at RA23I, a circuit extending from ground at RA205 for energizing the winding of R235 in series with the upper winding of the relay R240. The relay R235, upon operating, prepares, at RA237, various circuits, traced hereinafter, for energizing certain of the other relays shown in Figs. 2 and 3. At RA238, the relay R235 opens a point in the circuits, traced' hereinafter, for energizing the release magnets 221 and 351. At RA238, the relay R235 also prepares pulsing circuits, traced hereinafter, for respectively energizing the vertical magnet 246, the rotary magnet 342 and the operating magnet 356 of the minor switch 350. The relay R240, upon operating, prepares, at RA233, a holding circuit for itself and prepares, at RAZM, the above-mentioned circuit for energo'gizing the vertical magnet 246. At RA20I and RAZAZ, the relay R240 substitutes ground through the secondary winding of the transformer 201 for ground derived from the contact associated with RA242 in the above-traced loop 45 circuit including the two windings of the line relay R230. When the secondary winding of the transformer 207 is included in this loop circuit, the usual dial tone signal is transmitted through the transformer I01 to the receiver IOI provide 50 in the calling substation.

At RA236, the hold relay R235, upon operating, impresses ground potential upon the control conductor 20c of the trunk line 20, thereby to mark the connector switch of Figs. 2 and 3 as busy 55 in the bank contacts of the various line switches having access thereto. When groundpotential is impressed upon the indicated control conductor, the relay R150 is energized over a circuit which may be traced as extending by way of the grounded conductor 200, the secondary winding of the transformer I20 and the winding of RI50 to battery. When energized over this circuit, the relay RI50 operates to complete, at RAISI, an obvious path for impressing ground potential upon the control conductor of the trunk line section extending to the bank contacts of the line switch I0, thereby to maintain this line switch operated. At RAI52, the relay RI50 completes an obvious circuit for energizing the slow-torelease relay RI40, causing the last-mentioned relay to operate and complete, at RAMI an obvious multiple path for impressing ground potential upon the last-mentioned control conductor. At RAI42, the relay RI40 prepares a circuit for 75 energizing the relay RI20. The operation of the times.

two relays R140 and RI50 also results in the energization of the lower winding of the electropolarized relay RI30 in an obvious manner. The direction of current flow through the upper winding of this polarized relay is, however, such that the relay does not operate at this time. Following the above-described operations, the connector switch, as shown in Figs. 2 and 3, is conditioned to respond to the impulses of the first digit to be dialed at the calling substation A.

After removing the receiver IOI from its supporting hook, the calling party should deposit the coin representing the charge for local calls in the coin-receiving means provided at the subst'ation A. Following this operation the calling party may proceed to dial the digits of the directory number designating the desired substation B. When a coin is deposited in the coin deposit channel of the coin-receiving means,-the coin controlled mechanism operates to move the contact springs I09 into engagement, thereby to connect the windings of the polarized magnet I01 and the serially related discharge lamp I08 between the line conductor a and ground. At this time the voltage of the exchange battery as impressed between the line conductor a. andground through the windings of the two relays R230 and R225 is insumcient to cause current fiow through the discharge device I08. Accordingly, the windings of the electromagnetic device I01 are not energized at this time. During the dialing operation and each time the dial of the calling device I00 is moved off normal, the shunt springs I II of this device are moved into engagement to complete obvious paths for short-circuiting the transmitter I00 and the receiver IOI. Also, during each return movement of the dial, the pulsing springs IE8 are opened and closed a number of times depending upon the numerical value of the digit dialed. At the end or each return movement of the dial the shunt springs II'I are opened in the usual manner to interrupt the above-mentioned short-circuiting paths.

The line relay R230 responds to the impulses of the first digitdialed at the calling substation by completing the above-mentioned operating circuit for the vertical magnet 206 one or more Assuming, for example, that the directory number designating the desired substation B is "I15, the line relay R230 restores and reoperates seven times during the impulses of the first digit so that seven current pulses are transmitted to the vertical magnet 246. The circuit for energizing this vertical magnet may be traced as extending from ground at RA205 by way of RA23I, RA238, RA244 and the winding of the magnet 200 to battery. A branch of this circuit extends by way of RA243 and the lower winding of the slow-to-release relay R200 to battery. gized, the wipers 36I to 360, inclusive, are elevated one step so that at the end of the first digit of seven impulses these wipers are left standing opposite the seventh level of bank contacts. As the indicated wipers are operated to the first vertical oil-normal position, the off-normal springs 245 are moved into engagement to complete an obvious path for short-circuiting the upper winding of the relay R200. By virtue of the completion of the above-mentioned branch circuit including the lower winding of the relay R240 and the slow-to-release characteristic of this relay, it remains operated until shortly following the end of the first digit. Due to its slow-to-release characteristic, the hold relay R23! also remains operated during impulsing. Attheendoitheflrstdisitanddurinstheinterdlsitpwsebetweentheflrstcndseccnddigits, thelinerelaymllremainsoperatedi'oresumcientlylonxtimeinternltoccusetherestomflonoitheneleym. Uponrestorins.therelay Rlllopmatmllapointinthecimiitror its lower winding and opens, at mm, theebove-tncedimnilsinzcircuitincludinzthe windinzoitheverticalmasnetlll. AtRAIll andRA2l2,therelayR2llrmovcsthesecondarywindingotthetmnstormerll'ln'mnthe loopcircuitextendinatothecsllingsubstaflcn, therebyto tenninatethedieitonelitnllbeinz transmittedtotheccllinxmhscrlber.

'lhehnpulsesottheseconddisitdiniedatthe cailinzsuhstationarerepeatedthroughopenflonofthelinerelaymlltotherotarymaznet Ill. lloreparticularlymsthelinerelayrestores attheoteeehimpuiseotthesecond dizlhacircuitiscompletediorenergizingthe mtarymagnetfliinserleswiththeslow-w' 5 and R32! remain operated throughout the secondandearhserlesotimpiflses. Upon operating, the relay B32! opens, at EH23, a point in an alternative circuit, traced hereinatteniorthebusyrelaymll. At

BASH and its associated resting contact, the

relaymllopensapointinthecirclntntraeed ,tur energizing thelowerwinding of thelineswitchingrelaymil. AtRAHI and RAIII, the'relay Bill completes the line test mcircnitincludingthewindingotthehusyrelay Rlllwherebythisbusyrelayiseach time the wiper! lil to l, inclusive, encounter asetotcontaetstelmiuatingabusyline. At RAJ", the relay R32. opmsapointtnthepnth,

es tracedhereinattenforimbusytonevoitaseupontheloopcircuitextendingtcthecallinzsuhstation.

Immediately the wipers iii to I", inclusive. aremovedinto t withthe contacts 70thecalled1inel2,thlslineistested overtheebove-menflonedtestdrcuitincluding thewlndingofthebusyrelaylull. thecalledlinetobebusyettheflmeitisthus m 1 8! r yis overthis "circuit whichextendshywayolthe grounded an thebmyrelay. inzcircultiorthebuayrelayextendsbywayo! the grounded release conductor C2. RM", RAM! andihalociatedrestin contachwli andthewindingoitherelaymlltobattery. At RAJ", the relay R32. completes the above- Itispointedoutth'atiollowing operation oithe busyrelayRtllthediaiinzoithethii-ddieitat thecallinssubstatimiswithmiteflectsincewith the relay Rlll operated the pulsing circuit'ior therotarymagnetfllilheldopenatthearmatures RA: and RAIII and the circuit for enersizing the operating magnet ill of the minor switch lilisnlsointcmipted at these two points. HenceJithecallinzpartycontinuesthedialing opemtionanddiaisthethirddigit.theoniyresponsetotheimpulsesotthisdixitisthe alternote restoration and operation of the line relay R2". Following the operation of the busy reiayRlll,inthema-nnerjustexplained,noturther operaflonoftheapperatus occurs until the 'nisclearedoutattheculiingsuhstation. Themunnerinwhichtheswltchtreinis released when the calling subscriber replaces the receiver Ill upon its supporting hook III is explsined in detail hereinaiter.-

thecalledline litobeidleatthe time it is selected, battery potential is present upon the private or control conductor thereof sothatthelmsyrelaylttllisnotcnergizedover the previously traced test circuit. Shortly foilowingtheselectlnnotthelineanddm'lngthe interdigit pause between the second and third digits, the two relays Bill and R31. sequentially restoreinthemannerpointed outabove. The relay R3, upon restoring, completes the abovementioned circuit for energizing the slow-tooperate line switching relay Bill, this circuit extending by way 0! the grounded release conductor C269, RA302, the lower winding of R330; RA32I, RA332 and the wiper 363 to the negative battery terminal as connected to the private conductor of the called line I2 through the windings of the cut-oil relay conventionally embodied in the line switch l5. When its lower winding is energized over this circuit, the relay R330 first completes, at the "2! contacts associated with RA330, a holding circuit for itself, this holding circuit extending by way oi. the grounded release conductor (221i, RA334 and the upper winding of R330 to battery. Thereafter the relay R330 opens, at RA333, a point in the abovetraced test circuit including the the winding of the busy relay R300, interrupts, at RA332, its own operating circuit as traced above, and completes, at RA332, a path for impressing. ground potential upon the private conductor of the called line for the purpose of marking this line as busy in the bank contacts of the other connector switches having access thereto. This path extends by way of the grounded conductor C21l, RA332 and the private wiper 363 to the private conductor of the called line. At RA33I, the relay R330 opens a point in the above-mentioned circuit for energizing the trunk hunting relay R325 and prepares a circuit, traced hereinafter, for energizing the coin refund control relay R300. At RA335, the relay R330 prepares the above-mentioned circuit for energizing the operating magnet 356 of the minor switch 350' in accordance with the impulses of the third and, final digit of the directory number designating the called substation B. At RA336, the relay R330 prepares a point in the circuit for energizing the ringing control relay R250. Finally, at RA331, the relay R330 opens a point in the above-traced path for impressing busy tone voltage upon the calling loop circuit. Following operation of the relay R330, the operating magnet 355 is conditioned to respond to the impulses of the third digit of the directory number'designating the called substation.

Each time the line relay R230 restores during the impulses of the third digit, the above-mentioned circuit is completed for energizing the magnet 356, this circuit extending from ground at RA205 by way of RA23I, RA238, RAMA, C212, RA303, the winding of R3 l0, RA335 and the winding of the magnet 356 to battery. When energized over this circuit at the beginning of the first impulse of the third digit, the relay R3 l0 operates to complete the operating circuit for the relay R320, which latter relay, in turn, operates to open, at RA323, the above-mentioned alternative circuit for energizing the busy relay R300. The two slowto-release relays R310 and R320 remain operated throughout the impulses of the third digit. Each time the operating magnet 356 is energized during the impulses of the third digit, it functions to advance the wipers 353 and 354 one step so that, at the conclusion of the third digit of five impulses, these wipers are left standing in engagement with their respective associated fifth contacts. When the indicated wipers are stepped to their respective first oif-normal positions, the off-normal springs 358 are moved into engagement to prepare the alternative circuit for energizing the busy relay R300. This circuit is completed short-v ly following the end of the third digit and in response to the sequential restoration-of the two slow-to-release relays R3l0 and R320. Specifically, this circuit extends from ground by way of the springs R358, RA323 and the winding of R300 to battery. Upon operating, the relay R300 prepares, at RA303. the circuit for energizing the relay R345. At RA303, the relay R300 prepares the above-mentioned circuit for energizing the release magnet 351. At RA304, the relay'R300 prepares the circuit for energizing the ringing control relay R260. The last-mentioned circuit is completed shortly following the operation of the busy relay R300 and at the beginning of the next cycle of operation of the ringing interrupter switch forming a part of the ringing apparatus conventionally provided in the community exchange in common association with the various connector switches of the exchange. This circuit may be traced as extending from ground by way of the pickup conductor C320, RA336, RA304, C213, RA263 and the winding of R260 to battery. When energized over this circuit the relay R260 operates to complete a holding circuit for itself, which holding circuit extends from ground at RA231 by way of RA262, RA263 and the winding of R260 to battery. Following the completion of this circuit the relay R260 opens, at RA233 and its associated resting contact, a point in its operating circuit as traced above. pletes a circuit for projecting over the called line 'i 2 coded ringing current of the particular character corresponding to the called substation B, as

selected by the minor switch 350. More particularly, the circuit traversed by the ringing current may, in the present case, be traced as extending from one terminal of the ringing current generator by way of contacts controlled by the abovementioned interrupter switch, not shown, C310, the fifth contact of the set 352, the wiper 353, C266, RA25I, RA20i, RA20I, C261, RA300, the wiper 36L one side of the line I2, the ringer and condenser bridged between the conductors of the line 12, the other side of the line 12, the wiper 360, RA306, C216, RA206, RA260, RA253, C210, the wiper 353, the fifth contact of the set 35!, C215, the lower winding of R250, RA231 and the exchange battery to the other side of the ringing current source. The resulting operation of the signal device provided at the called substation B serves to signal the subscriber at this substation that his substation is being called to the exclusion of other substations associated with the line l2. A portion of the ringing current is by-passed by way of the condensers 280 and 23! and the calling loop circuit to energize the receiver provided at the calling substation, thereby to signal the calling party that the called substation is being rung.

The desired conversational circuit between the calling and called substations is completed when the call is answered at the called substation B. More particularly, when the receiver at the called substation is removed from its supporting hook, the hook switch embodied in this substation operates to connect a direct current bridge across the conductors of the line l2, thereby to complete a circuit, substantially similar to that traced above and traversed by the ringing current, for energizing the lower winding of the slow-acting cut-01f relay R250. When energized by direct current traversing this circuit, the relay R250 operates to complete, at the X contacts associated with RA252, a circuit, extendingfrom ground at RA231, for energizing its upper winding. Following the completion of this circuit, the relay R250 completes its operation to open, at RA25| and RA254, two points in its operating circuit and two points in the above-traced circuit traversed by the ringing current, thus arresting the ringing operation and terminating the ring-back tone signal. At

these same armatures and their respective associated working contacts, the relay R250 completes At RA26| and RA263, the relay R260 comthe desired conversational circuit between the calling and called substations and, in so doing, completes a loop circuit extending to the called substation. This loop circuit includes the windings of the back-bridge relay R2l0 and may be traced as extending from ground at RA202 by way of the lower winding of R2l0, RA204, RAIN,

RA200, C210, RA948, the wiper 204, one side of the called line l2, the direct current bridge connected between the conductors of the line l2, the other side of the line I2, the wiper 201, M240,

C261, RAZBI, RA20I, RA25I and the upper wind- RA2I I, an obvious multiple path for impressing ground potential upon the control conductor 20s of the trunk line 20. At its armatures-RA2I2 to RA2I4, inclusive, the relay R2I0 reverses the direction of current flow over the calling loop circuit in the usual manner.

The back-bridge relay R2l0, upon operating, also completes, at RA2I1, an obvious circuit for energizing the slow-to-operate relay R200 in parallel with the slow-to-release relay R290. The relay R290 now operates to complete a path for impressing booster battery potential upon the control conductor 20c, this path extending from the positive terminal of the booster battery current source 294 by way of the resistor 292, RM and RA2 92 to the conductor 20. Aiter this path is completed the control conductor 20s is disconnected from ground at RA292 and its associated resting contact. Shortly following the operation of R290, the relay R290 operates to complete, at RA291, an obvious holding circuit for itself. At RA290, the relay R290 opensthe operat ng circuit for the relay R290. The relay R290 restores its armatures RA29i and RA202 after an interval, thereby to disconnect the conductor 20c from the booster battery source and to reconnect this conductor to ground. Thus, it will be apparent that booster battery potential is impressed upon the control conductor 20s for a short time interval immediately following the completion of the desired talking circuit between the calling and called substations. In the present case the application of positive booster potential to the conductor 20c is without eflect other than to increase the energization of the relay Rl00 On calls originating at regular substations oi the -system, however, and routed through the con}- nector switch of Figs. 2 and 3, the application of booster potential to the conductor 200 may be utilized, in a well-known manner, to control call metering devices associated with the calling lines. The application of booster potential to the control conductor 20 of the trunk line 20 may also be utilized to control the paystation trunk circuit apparatus shown in Fig. 6 in the manner described hereinafter.

When the relay R2 I0 operates to reverse the direction of current flow over the calling loop circult, the electropolarized relay R120 operates to prepare, at RAI3 i, a path, traced hereinafter, for impressing a positive or coin collecting potential of 110 volts upon the line conductor ii. in order to cause the electromagnetic device 101 to operate and collectthe coin depdsited in the coin-receiving means provided at the calling substation. As

explained previously, the relay R120 is of the type such that when once operated it remains in its operated position regardless of the direction of current flow through its operating or upper windins.

' The arrangement of the connector switch shown in Figs. 2 and 3 is such that the release or a switch train including this switch is entirely its hook before the connection is cleared out atthe calling substation, the only resulting operation is the release of the back-bridge relay R2 II to reverse the direction oi current flow over the calling loop circuit When, however, the calling party replaces the receiver ill upon the switchhook N4, the calling loop' circuit is interrupted at the springs -I I0 and ill, and the line relay R220 restores to interrupt'the circuit for. energizing the hold relay R220. The hold relay, upon restoring, completes, at RA220, the above-mentioned circuits tor energizing the release magnets 221 and 201. The circuit for energizing the magnet 221 extends irom ground at RA200 by way or RA22I, RA222, RA222, the oil-normal springs 224 and the winding of the magnet 221 to battery. When thus energized, the magnet 221 operates to cause the restoration of the wipers 201 to 204, inclusive, to rotary and vertical normal in the usual manner. If the back-bridge relay R210 is operated at the time the release magnet 221 is energized, the loop circuit extending to the called substation is interrupted during the release of the switching mechanism, thus causing the destoration of the back-bridge relay. Upon restoring, the relayR2i0 opens, at RA2I1, a point in the operating circuit for the relays R280 and R220. When the enumerated switch wipers are returned to their respective normal positions, the oil-normal springs 224 are opened to deenergize the magnet 221. The circuit for energizing the release magnet 201 extends from ground at RA220 by way or RA22I, RA222, C214, RA200 and the winding of the magnet 201 to battery. When this circuit is completed, the magnet 201 operates 'to cause the wipers 202 and 204 or the minor switch 200 to be returned to their respective home positions, at which time the ctr-normal springs 202 are opened to interrupt the above-traced alternative circuit for energizing the busy relay R200, causing this relay to restore and open, at RA200, the operating cir. cuit for the release magnet 201.

When the hold relay' R220 restores, in the manner explained above, it also interrupts, at RA221. a point in the common portion or the holding circuits for the relays R200, R200 and R220, causing all of these relays to restore. At this time ground potential is also removed from the private conductor of the called line l2, permitting battery potential to be impressed upon this private conductor through he windings oi the cut-on relay embodied in the line switch 10, thereby to mark the line i2 as idle. At RA220, the relay R220 opens the holding circuit for the relay R290, causing the last-named relay to restore. Following the restoration of the indicated relays and switching apparatus, the connector switch is fully released.

when the two relays R2i0 and R220 restore during the release of the connector switch,

, conductor 20c of the trunk line 20, thereby to dey ground potential is removed from the private energize the relay RI50. When ground potential is removed from the private conductor 20c of the trunk line 20, the connector switch shown in Figs. 2 and 3is marked as idle in the bank contacts of the line switches having direct access thereto. Upon restoring, the relay RI50, at RAI52, opens the operating circuit for the relay RI40 and completes a circuit extending by way of RAI42 for energizing the relay RI20. At RAISI, the relay RI50 opens one'of the multiple paths for impressing ground potential upon the private conductor extending to the bank contacts of the line switch I4. The relay RI20, upon operating, completes, at RAI2-I and RAI22, the above-mentioned path for impressing a positive or coin collect potential of 110 volts upon the line conductors a and b of the calling line I I. More particularly, the 110 volt source is connected across the discharge device I08 over a circuit which extends from the ungrounded terminal of the source by way of CI34, RAIN, RAI2I, the conductor a, the springs I00, the windings of the magnet I01 and through the discharge device I to the grounded terminal ofthe source. The magnitude of this voltage is such that the gas contained in the discharge device I08 is ionized to permit the flow of current therethrough, so that the windings of the magnet I01 are energized. The polarity of the current traversing the above-traced circuit following ionization of the device I00 is such that the armature associated with the magnet I01 is pivoted in a direction to cause the coin deposited in the coin deposit channel of the coin-receiving means to be directed into the coin collect channel in the usual manner. Operation of the armature associated with the magnet I01 also results in disengagement of the contact-springs I09 to interrupt the series circuit including the windings of the magnet I01 and the discharge device I08. Thus, the deposited coin is collected during the release of the operated switch train and after the conversation held over the established connection is terminated. Shortly following the energization of the magnet I01 the slow-to-release relay RI40 restores to open, at RAItI, the sec ond multiple path for impressing ground potential upon the private conductor extending from the trunk circuit apparatus I1 to the bank contacts of the line switch I4. At RAI42, the relay RI SU opens the operating circuit for the relay RI 20, causing the last-mentioned relay to restore. When the relay RI20 restores it disconnects ground from the private conductor extending from the apparatus I1 to the bank contacts of the line switch It and, in so doing, interrupts the circuit for energizing the lower windings oi the electropolarized relay RI30, causing the latter relay to restore. At its armatures RAIZI and RAI22, the relay RI20, upon restoring, also opens the above-traced path for impressing the positive coin collect potential upon the conductors Ila and b of the line II. When ground potential is removed from the private conductor extending between the apparatus I1 and the bank contacts of the line switch Hi, this switch is released in the usual manner and battery potential is substituted for ground upon the private conductor 0 of the calling line II, thereby to identify this line as idle in the bank contacts of the connector switches having access thereto. Thus, the apparatus involved in establishing the .the line switch I4 is caused to release.

connection between the substations A and B is mains in its restored position. When the usual busy tone signal is transmitter. to the calling substation, the calling party is expected to abandon the call by replacing the receiver IOI upon its supporting hook H4. In response to this operation, the calling loop circuit is interrupted and the relays R230, R235 and R300, which are the only operated relays in the connector switch, are caused sequentially to restore in an obvious manner. The hold relay R235, upon restoring, functions tov remove ground potential from the control conductor 20c and to complete, at RA230, the

previously traced operating circuits for the release magnets 221 and 351, thus causing the minor switch 350 and the switching mechanism of the connector switch to be restored to normal in the manner previously explained. When ground potential is removed from the control conductor 20 of the trunk line 20, the relay RI50 is deenergized and restores to complete the previously traced circuit for energizing the relay RI20. Upon operating, the relay RI20 completes, at RAI2I and RAI22, paths for impressing the negative potential of the 110 volt coin refund current source upon both conductors of the calling line II. More particularly, the voltage of this source is impressed across the electrodes of the discharge tube I08 over a circuit extending from the negative terminal of the coin refund current source by way of CI33, RAI3I, RAIZI, the conductor a, the springs I09, the windings of the magnet I01 and through the device I08 to the positive terminal of the coin refund current source. The magnitude of this voltage is such that the discharge device I08 is rendered conductive, so that the windings of the magnet I01 are energized by current traversing the circuit just traced. The direction of current flow over this circuit is such that the magnet I01 pivots its associated armature in a direction to cause the coin deposited in the coin deposit chute of the coin-receiving means to be directed into the coin refund channel of this means. Operation of the armature controlled by the magnet I01 also results in disengagement of the contact springs I00, whereby the circuit serially including the discharge device I08 and the windings of the magnet I01 is broken. Shortly thereafter the relays RI40 and RI20 are caused to restore in the order named and in the manner previously explained, the last-mentioned thereof functioning to disconnect ground from the private conductor extending from the trunk circuit apparatus I1 to the line switch It, whereby Thus, the operated switch train is fully released and the coin deposited by the calling party, incident to initiation of the call, is refunded.

Referring now to the operation of the apparatus to extend a connection to the operators position I9 in the central cflice, if it be assumed, for example, that the above-described call initiated at the substation A is a trunk call and further that the line switch 14 and the connector switch shown in Figs. 2 and 3 are utilized in completing Ethe desired connection, the calling party, after removing the receiver l0| from its supporting hook H4, dials the two digits of the directory number designating the operator's position l9. As explained above, the arrangement of the apparatus provided at the substation A is such that two digit numbers may be dialed without the deposit of a coin in the coin-receiving means. In response to the impulses of the first digit, the wipers 36l to 364, inclusive, of the connector switch are elevated to a position opposite the level of bank contacts terminating the link lines extending to the repeaters associated with the trunk lines extending to the central offlce, all in the exact manner previously described with reference to the call routed to the substation B. In this connection, it is pointed out that the uppermost level or levels of bank contacts embodied in the connector switch are utilized to terminate the indicated link lines. During the vertical movement of the wipers and when the wipers are moved to a position opposite the first of the contact levels terminating link lines extending to the two-way repeaters, the off-normal springs 209 are moved into engagement to prepare a circuit, traced hereinafter, for energizing the slowto-release switching-through relay R200. When a second digit of one impulse is dialed at the calling substation, the rotary magnet 342 is energized and operates to rotate the wipers 36l to 364, inclusive, into engagement with the first set of contacts in the selected contact level. Assuming that the link line l3 extending to the repeater I6 is terminated at the third set of contacts in the selected level and further that the trunk line I0 is the first available idle trunk line extending to the central office, the three relays R300, R320 and R325 cooperate with the rotary magnet 342 to cause the wipers to be rotated until they encounter the third set of contacts in the selected level. Thus, the private conductors of the link lines extending to the repeaters associated with the respective first and second interofiice trunk lines both have ground potential thereon by virtue of the busy condition of the associated repeaters. Accordingly, when the wiper 363 encounters the grounded contact of the first contact set during the first step taken bythe wipers 36l to 364, inclusive, the previously traced circuit is completed for energizating the busy relay R300, it being pointed out that the two slow-acting relays R3l0 and R320 are operated at this time. When the relay R3I0 restores shortly following the operation of the busy relay R300, it completes the previously mentioned circuit for energizing the trunk hunting relay R325, this circuit extending by way of the grounded private conductor of the first link line, the strap 316 between the private and extra control contacts of the first contact set in the selected level, the wiper 362, RA33I, RA30I, RA3I I, the armature 343 and the winding of R325 to battery. When this circuit is completed, the relay R325 operates to complete, at RA326, a holding circuit for itself, which holding circuit extends from ground at RA236 by way of C269, RA326, the armature 343 and the winding of R325 to battery. At RA321, the relay R325 completes a circuit for energizing the relay R320 and the rotary magnet 342 in parallel, one branch of this circuit extending by way of the grounded release conductor 02', RA321, RA3I2 and the winding of R320 to battery, and the other branch extending by way of C2", RA32I, RA335 and the winding of the magnet 342 to battery. By virtue of the completion of this circuit, the slow-to-release relay R320 is maintained in its operated position. The rotary magnet 342, when energized over the above-traced circuit, operates to step the wipers 36i to 364, inclusive, into engagement with the second set of contacts of the selected contact level and to open, at the armature 343, the holding circuit for the relay R325. Therelay R325 now restores to open, at RA326, a further point in its holding circuit and to interrupt, at RA32'I, the above-traced circuit for enrelay reoperates to recomplete, at RA326, its holding circuit and to recomplete, at RA32'I, the circuit for energizing the relay R320 in parallel with the rotary magnet 342. As a result, the wipers 36! to 364, inclusive, are operated into engagement with the third set of contacts of the selected level, which contacts are assumed to terminate the conductors of the link line l3 associated with the idle interofiice trunk line l0. It will be understood, in view of the foregoing explanation, that in any case the interrelated operation of the relay R325 and the rotary magnet 342 continues until the wipers 36! to 364, inclusive, are advanced into engagement with a set of contacts terminating an idle one of the link lines or until all of the link lines have been tested.

Since, in the present case, the third link line I 3 is assumed to be idle, negative battery potential as derived through the winding of the relay R5'l0 is present upon the control or private a conductor I30 so that the trunk hunting relay R325 is not energized over the previously traced test circuit when the wipers 36| to 364, inclusive, encounter the contacts terminating the conductors of the line l3. Accordingly, the relay R325 remains in its restored position and the step-bystep operation of the wipers is arrested. Immediately the wiper 363 is moved into engagement with the contact terminating the private conductor |3c having negative battery potential thereon, the busy relay R300 restores to prepare the previously traced circuit for energizing the lower winding of the line switching relay R330. Shortly thereafter the relay R320 restores to complete the last-mentioned circuit. The relay R330 now operates to complete, at RA334, its holding circuit, as traced above, and to open, at RA333, a further point in the circuit for energizing the busy relay R300. At RA33I, the relay R330 prepares the circuit for energizing the relay R340. At RA332, the relay R330 opens a point in its operating circuit and completes a path for impressing ground potential upon the private or control conductor I38, this path extending by way of the grounded conductor C2'H, RA332 and the wiper 363 to the conductor I30. At RA334, the relay R330 also completes a circuit for energizing the switching-through relay R200, this circuit extending from ground at RA231'by way of C2", RA334, C210, the off-normal springs 209, the secondary winding of the transformer M6 and the winding of R200 to battery. Upon operating, the relay R200 completes, at RA204, a multiple path including the primary winding of the transformer M6 for impressing ground potential upon the private conductor 20 of the trunk line 20, thereby to maintain the relay Rl50 energized. At RA208', the relay R200 completes the circuit for energizing the relays R290 and R295, thereby to cause the sequential operation of these two relays followed by the restoration of the relay R290, in the manner previously explained. During the interval when the relay R290 is operated positive booster battery potential is substituted for ground potential upon the conductor 20. The relay R295, upon operating, completes a holding circuit for itself, this holding circuit extending from ground by way of the left winding of the transformer 2H5, RA204; RA291 and the winding of R295 to battery.

At RA20| and RA206 and their respective associated armatures RA202 and RA201, the relay R200, upon operating, connects the trunk line conductors 20B and 20b to the link line conductors C261 and C216, thereby to switch the calling loop circuit through to the repeater 10. At RA202 and RA201 and their respective associated contacts R0203 and R0208, the relay R200 opens two points in the loop circuit as initially established and including the windings of the relays R225 and R230, thereby to cause the sequential restoration of the relays R230 and R235. Before the hold relay R235 restores to remove ground potential from the respectiverelease conductors C269 and 021i, however, multiple ground potential is impressed upon the conductor C21l in the repeater l8 for the purpose of maintaining. the relays R200, R295 and R330 operated. Thus, when ground potential is impressed upon the private conductor. i3c of the link line I3, this line is marked as busy in the bank contacts of the other connector switches having access thereto and a circuit is completed for energizing the slow-acting relay R510. This circuit extends by way of the grounded conductor I30, RA562 and the winding of R510 to battery. Upon operating, the relay R510, at RA51| and RA512, extends the calling loop circuit through the windings of the repeating coil 520 and the windings of the line relay R400 so that the last-mentioned relay is energized thereover. Upon operating, the'relay R400 prepares, at RA402 and RA403, a circuit, traced hereinafter, for energizing the relays R530 and R540 in series. At RA40I, the relay R400 completes an obvious circuit for energizing the slow-to-release'hold relay R4l0. The lastmentioned relay, in turn, operates to prepare, at RA4H, a circuit for energizing the relay R460 and to complete, at RA4I2, an obvious circuit for energizing the relay R420. When the relay R420 operates, it completes, at RA422, two multiple paths for impressing ground potential upon the private conductor I36; one of these paths extending from ground at RA453, the other path ex- .tending from ground through the winding 466 and both thereof extending by way of RA422 to the private or control conductor I30. The completion of these paths prevents the release of the operated relays R330, R295 and R200 in the manner indicated above. The relay R420, upon operating, opens, at RA42I, a point in the circuit, traced hereinafter, for energizing the relay R560. At this same armature, the relay R420 prepares a circuit for energizing the pendulumtype relay R450. At RA423, the relay R420 prepares a circuit for energizing the ring cut-oi! relay R430 and, in so doing, completes a circuit for transmitting ringing current over both sides of the trunk line 10 to energize the signal device 502 provided at the operator's position l9. The circuit traversed by the ringing current extends from one terminal of the ringing current source by way of C438, the condenser 431, RA435, RA423, C503, an obvious simplex path including the line conductors i, and Nb of the line l0,

' the condenser 503, the winding of the signal device 502, the contact springs 506, and the exchange battery to the other terminal of the ringing current source. The resulting operation of the signal device 502 indicates to the operator that an incoming call on the line I 0 should be answered. At RA424, the relay R420 completes a circuit for transmitting the usual ring-back tone signal current to the calling substation. More particularly, the high potential terminal of the ringing current source is connected to one side of the calling loop circuit over a path including the conductor C438, the condenser 431, RA436, RA424 and C504. When this path is com: pleted, ringing current is caused to traverse the calling loop circuit to energize the receiver provided at the calling substation A, whereby the the above-traced circuit for energizing the sig nal device 502. Simultaneously the springs 501 are moved into engagement to complete the circuit for energizing the relay R430, this circuit extending from ground by way of the switch springs 509 and 508, the springs 501, the pulsing springs of the calling device 504, the simplex loop including both sides of the line l0, C583, RA423, RA434, the upper winding of R430 and RA433 to battery. When energized over this circuit, the relay R430 closes the X contacts associated with RA43I to complete an obvious holding circuit for itself. Thereafter th relay R430 fully operates to complete a circuit for energizing its two windings in series, this circuit extending from ground at RA453 by way of RA422, RA43i, the upper winding of R430, RA433, RA432 and the lower Winding of R430 to battery. Following the completion of this circuit, the relay R430 opens, at RA433 and its associated resting contact, a point in its initially completed operating circuit. At RA435 and RA436, the relay R430 opens the above-traced circuits for transmitting ringing current over the line G0 to the operators position l9 and back over the calling loop circuit to the calling substation A, thus terminating the ring-back tone signal. At RA434, the relay R430 completes the previously mentioned circuit for energizing the two relays R530 and R540 in series, this circuit extending by way of the grounded conductor C583, RA423, RA434, the resistor 404, RA403, RA402, C58l, the winding of R540 and the two windings of R530 to battery. Due to the relatively high resistance of the series connected windings of R530, the relay R540 does not operate when this circuit is completed. The relay R530, however, operates to complete, at RA631, the circuit for energizing the pendulumtype relay R450, this circuit extending from ground by way of RA531, C511, RA421 and the winding of R450 to battery. When energized over this circuit, the relay R450 attracts its associated armature RA455 to initiate vibration of the weighted armature 456. At RA454, the relay R450 completes an obvious holding circuit for the relay R420. At RA453, the relay R450 opens one of the previously traced multiple paths for impressing ground potential upon the private conductor 13 and, in so doing, removes the short circuit from the transformer winding 466 so that paystation tone current is caused to traverse this winding. More particularly, paystation tone voltage is impressed, through the condenser 22, upon the control conductor c of the calling line 11 by the alternating current source 21. This potential is impressed by means of the transformer 124 upon the private conductor 20 and is thus applied to the primary winding of the transformer 216. The transformer 216, in turn, impresses the paystation tone potential upon the conductor C210 the last-mentioned conductor being connected through the private wiper 363 to the control conductor 13 of the link line 13. Thus, the voltage across the secondary winding of the transformer 216 is impressed across the primary winding 466 of the transformer 465. When the relay R450 operates, the induced voltage developed in the secondary winding 461 of the transformer 465 is impressed upon the line conductors C513 and C585 of the repeater 18 over a path including the condenser 468 and the two armatures RA451 and RA442. 'As a result,

paystation tone current is caused to traverse the windings of therepeater 520 so that the usual paystation tone signal is transmitted by way of the trunk line 10 and the repeater 500 to the receiver of the operator's telephone set. Through reproduction of this voltage, the operator is informed that the calling substation is of the paystation type. A predetermined time interval following energization of the relay R450, the vibrating armature 456 settles into resting engagement with its associated armature RA455 to hold completed an obvious circuit for energizing the slow-to-operate relay R440. The relay R440 operates after an interval to complete, at RA441, an obvious path for short-circuiting the winding 466 of th transformer 465, thereby to terminate the paystation tone signal and to complete a multiple path for maintaining ground potential upon the control conductor 13c. At RA442, the relay R440 disconnects the secondary winding 461 of the transformer 465 from the line conductor C585.

The relay R450, upon operating, also functions to reverse, at its armatures RA451, RA452, RA458 and RA459, the direction of current flow over the calling loop circuit in an obvious manner. As a result of this current reversal, the relay R130 included in the trunk circuit apparatus 11 is caused to operate to prepare, at RA131, the previously traced paths for impressing the positive potential of the volt coin collect current source upon the line conductors Ila and ||b of the calling line 11.

If the operator desiresto recall the paystation tone signal she may do so by momentarily withdrawing from the jack 501 the plugterminating her telephone set. When -the call and answer plug is withdrawn from the jack 501, the springs rent flow over the calling loop circuit. Since the relay R of the trunk circuit 11 is'nowbp'rated, the last-mentioned reversal of the direction of current flow over the calling loop circuit is without effect. When the operator reinserts the plug terminating her cord circuit in the jack 501, the previously traced operating circuit for the relay R530 is recompleted, causing this relay and the relay R450 sequentially to operate in the order named. As a result, paystation tone current is again caused to traverse the winding 466 of V the transformer 465 and the secondary winding 461 is again connected between the line conductors C513 and C585. After a predetermined time interval required for vibration of the weighted armature 456 to cease, the slowto-operate relay R440 operates to terminate the signal in the manner explained above.

After the connection between the operator's position 19 and the calling substation A is established in the manner just explained, the op-- erator, upon ascertaining the party or substation desired by the calling party, may instruct the calling party to make the appropriate coin deposits. It may occur that an improper coin deposit is made by the calling party, in which case the operator may desire to refund all of the deposited coins and request a second deposit of the coins representing the assessed charge. A refunding operation of this character may be performed under the control of the operator at any time. To this end, the operator momentarily operates the key 505 to its off-normal position. In response to this operation, the contact springs 508 and 510 are closed and the springs 508 and 509 are disengaged. As a result, the booster battery current source 511 and the resistor 512 are serially included in the previously traced circuit for energizing the windings of the two relays R530 and R540 in series. The increased current fiow over this circuit causes operation of the relay R540. Upon operating, the relay R540 completes, at RA541, the previously mentioned circuit for energizing the relay R460, this circuit extending from ground by way of RA541, C515, RA411 and the winding of R460 to battery. Upon operating, the relay R460 completes, at RA462, a local loop circuit including the resistor 464 for maintaining the line relay R400 operated. At RA461 and RA463, the relay R460 opens two points in the calling loop circuit. At these same armatures and their respective associated working contacts, the relay R460 impresses the negative 110 volt potential of the coin refund current source upon both sides of the calling loop circuit. As a result, the discharge device 108 is rendered conductive and current flows through the windings of the magnet 101 over a circuit extending from the positive terminal of the 110 volt source by way of the discharge device 108, the windings of the magnet 101, the contact springs 109, the conductor 11B, RA121, the conductor 20a, RA202, RA20I, C261, RA345, the wiper 361, the conductor 13a, RA461 and C133 calling party through the coin refund chute of the coin-receiving means. When the key 506 is released and allowed to restore to its normal position, the springs 508 and l0 are disengaged and the springs 508 and 509 are moved into engagement. Accordingly, the booster battery source 5 is excluded from the series circuit including the windings oi. the relays R530 and R540, causing the last-mentioned relay to restore. Upon restoring, the relay R540 opens the previously traced operating circuit for the relay R460. The relay R460, in turn, restores to disconnect the line conductors 13a and I31; from the negative terminal of the coin refund current source and to extend the calling loop circuit to the line terminals of the line relay R800. At RA662, the relay R460 also interrupts the local loop circuit including the windings of the line relay R000.

After the correct coin deposits have been made by the calling party, the operator attending the position I9 may extend the connection to the desired substation and complete the desired conversational circuit between the calling and called substations in the manner conventionally employed in manual ofiice practice. During the release of the connection and when the operator withdraws the plug terminating her cord circuit from the jack 501, the contact springs 501 are disengaged to open the series circuit including the windings of the relays R530and R540. I Thus, the relays R530, R550 and R650 are caused sequentially to restore in the manner previously explained. When the calling subscriber thereafter replaces the receiver IOI upon the supporting hook I I5 to interrupt the calling loop circuit, the relays R500. R410, R520, R430 and R510 are caused sequentially to restore in an obvious manner and in the order named. The relay R420, upon restoring, disconnects the private conductor 13: from ground, thus interruptin the holding circuit for the operated relays R330, R295 and R200 of the connector switch shown in Figs. 2 and 3. plates, at RA205, the previously traced circuit for energizing the release magnet 221, thus causing the wipers 36I to 365, inclusive, to be restored to rotary and vertical normal in the usual manner. When these wipers are returned to their respective home positions, the operating circuit for the release magnet is opened at the oiT-normal springs 224. In addition, the oil-normal springs 209 are disengaged to open a further point in the operating circuit for the relay R200. At RAZM, the relay R200, upon restoring, disconnects ground potential from the private conductor c of the trunk line 20, thus causing the restoration of the'relay RI50 followed by the operation of the relay R120. When the relay R120 operates, it connects the line conductors a and b of the calling line II to the positive terminal of the 110 volt coin collect current source so that the magnet I01 is energized by current of the proper polarity to cause the armature associated with this magnet to operate in the manner required to pass the deposited coins into the coin collect chute of the coin-receiving means. Shortly following the operation of the relay RI20, the relay R140 restores to cause the sequential restoration of the relays RIM and The relay R200, upon restoring, com- R130 in the manner previously explained. With the three relays RI20, RI40 and Rl50 all released,

the private conductor extending from the ap-' paratus l1 to the bank contacts of the line switch I4 is disconnected from ground, permitting the line switch I8 to release and remove ground potential from the private conductor I '0 of the calling line. Thus, the connection is fully released and the apparatus involved therein is conditioned for further use.

In the event the connection is released at the calling substation beforeit is cleared out at the. operators position I9, the relays R400, R4|0,

R420, R430, R510, R650 and R040 are all caused to release in an obvious manner. When these relays are restored to normal, ground potential is removed from the private conductor I3e of the link line I3 so that the connector switch shown in Figs. 2 and 3 is released in the manner pointed out above. Also, the trunk circuit apparatus l1 operates to cause the coin collecting operation to be performed, after which it releases to initiate the release of the line switch 15. During the release of the indicated relay equipment embodied in the repeater i8 and when the relay R020 restores, an alternative circuit, traced hereinafter, is completed for energizing the relay R530, whereby this relay, the relay R560, the relay R510 and the relay R550 are caused to reoperate to extend a connection through the line switch I6 to an idle one of the connector switches provided in the community exchange, all in the manner pointed out immediately hereinafter.

To initiate, at the operators position I9, a call intended for one 'of the substations associated with a line terminating at the distant communityexchange, the operator inserts the plug terminat- 505 and 500, the jack springs 501, the pulsing springs of the calling device 506, the simplex loop including the conductors We and Nb of the line I0, C583, RA423, the resistor B06, RA403, C562, RA552' and the lower winding of R530 to battery. The relay R530, upon operating, prepares, at RA532, a loop circuit to the line switch I6 associated with thelink line 13. At RA-53I, the relay R530 completes a circuit for energizing the upper winding of the relay R560, this circuit extending from ground at RA53I by way of C511, RA42I, C516 and the upper winding of R560 to battery. The relay R560, upon operating, completes, at RA562, a circuit for energizing the slow-acting relay R510, this circuit extending from ground at RA53I by way of C511, RAQZI, C516, RA562 and the winding of R510 to battery. At RA563, the relay R560 prepares a circuit, traced hereinafter, for energizing the relay R550. At RA56I and RA566, the relay R560 prepares two additional points in the above-mentioned loop circuit extending by way of the line l3 to the line switch I6. This loop circuit is completed in response to operation of the relay R510 and may partially be traced as extending by way of the line conductor I311, RA46I, RA45I, C513, RA51I, the upper right winding of the transformer 520, RABBI, RA532, the upper winding of R550, RA564, the lower right winding of the transformer 520,.RA512,

vided at the called substation A will be collected, the operator attending the position i9 momentarily operates the key 505 to cause the operation of the relay R540 in the manner previously described. Upon operating, the relay R540 completes, at RA54I. a path including the conductors C515 and C514 for impressing ground potential iipon both sides of the loop extend ing by way of the line I3 and the line switch l6 to the connector switch shown in Figs. 2 and 3. As a result, the differentially wound relay R225 is unbalanced and operates. Upon operating, the relay R225 completes, at RA226, an obvious circuit for energizing the relay R220, which latter relay, in turn, operates to complete, at RA222, an obvious holding circuit for itself. Thus, the relay R220 is held in its operated position after the key 505 is restored to normal to cause the sequential restoration of the relays R540 and R225. Upon operating, the relay R220 opens, at RA223, a point in the previously traced circuit for energizing the release magnet 221. At RA22I, the relay R220 disconnects the conductor C268 from the negative terminal of the 110 volt coin refund current source and connects this conductor to the positive terminal of the 110 volt coin collect current source. Following the operation of the relay R220, the operator may cause the coins deposited in the coin-receiving means provided at the substation A to be collected before the desired conversational circuit between another substation of the system and the substation A is established, or, alternatively, permit the deposited coins to be collected during the release of the established switch train. In the event the operator desires to collect the coins before the connection is set up, the calling device 504 is operated to again interrupt the circuit for energizing the relay R530, causing this relay and the line relay R230 of the connector switch sequentially to restore in the order named. Upon restoring, the relay R230 completes the previously traced circuit for energizing the relay R345, whereby the last-named relay is caused to operate to connect the positive terminal of the 110 volt coin collect current source to each side of the called line H over the paths traced above. The magnet I01 of the coin control mechanism provided at the station A is, in this case, energized by current of the proper polarity to cause the deposited coins to be routed from the coin deposit channel of the coin-receiving means into the coin collect channel; 7

As indicated above, the following operation of the relay R220, the coins deposited in the coinreceiving means provided at the called substation A will also automatically be collected during the release of the operated switch train. The release of the switch train is entirely under the control of the operator attending the position l9. More particularly, when the connection is cleared out at the operatorfs position IS, the relays R530 and R230 sequentially restore and the relay R345 reoperates to cause the coin collecting operation to be performed at the substation A in the manner pointed out above. Shortly following the operation of the relay R345, the hold relay R235 restores to open, at RA231, the holding circuit for the relay R220 and to remove, at RA236 and 'RA231, ground potential from the private conductors 20c and l3c. The relay R220, upon restoring, disconnects, at RA22 I, the line conductors of the called line from the coin collect current source and completes, at RA223, the previously traced circuit for energizing the release magnet 221, thus causing the wipers 36| to 364, inclusive, to be restored to rotary and vertical normal. From this point on, the release of the connector switch shown in Figs. 2 and 3 and of the line switch I6 is accomplished in theexactmanner described previously. When ground potential is removed from the private conductor l3c of the link line l3, the relays R550 and R560 are deenergized and restore. The relay R510 is deenergized and restores shortly following the restoration of the line relay R530 to open the operating circuit for R510 as traced above. Thus, the repeater I8 is fully released and all of the apparatus utilized in setting upthe connection is conditioned for further use.

From the foregoing explanation, it will be apparent that on local calls originating at one of the pay stations served by the automatic switching equipment of the community exchange, the coin refunding and coin collecting operations are performed under the control of trunk circuit apparatus, such, for example, as the apparatus l1, after the calls are terminated and during the release of the switch trains through which the calls are routed. On trunk calls routed from the pay stations to the operators position I 9, on the other hand, coin refunding operations may be performed at any time after a connection to the operators position is established under the control of the operator and through operation of the apparatus provided in the repeater associated with the interoffice trunk line in use. On

such trunk calls, however, coin collect operations are only performed after the connection in use is cleared out and during the release of the operated switch train, the coin collect operations being controlled by trunk circuit apparatus, such, for example, as the apparatus l1, terminating the trunk line extending to the connector switch in use. Finally, on delayed calls originating at the operators position I9 and routed to substations of the pay station type served by the automatic switching apparatus located at the community exchange, coin refunding and coin collecting operations may both be performed under the control of the operator at any time after a connection is set up between the operators position and the called substation, these coin refunding and coin collecting operations being obtained through appropriate manipulation of the calling device 504 and the key 505 and the resulting operation of the control apparatus provided in the repeater and the connector switch in use.

Referring now more particularly to Fig. 6 of the drawings, the trunk circuit apparatus there illustrated is arranged for booster battery control and may be substituted in the system of Figs. 1 to 5, inclusive, for the trunk circuit apparatus H. In brief, the apparatus shown in Fig. 6 comprises a pay station tone repeating transformer 624, a line switching relay R600, a coin collect control relay R6I0 of the marginal type, and a pair of control relays R620 and R630 arranged to control the energization of the line switching relay R600. In order to substitute this apparatus for the apparatus l1 in the system shown in Figs. 1 to 5, inclusive, the terminals IN to 166, inclusive, may be disconnected from the trunk circuit l1 and connected to the terminals 66i to 666, respectively.

With the apparatus of Fig. 6 connected in the manner just explained, if a connection is routed through the line switch l4 to the connector switch of Figs. 2 and 3, the application of ground 

